Clinical experience and published studies indicate the effectiveness of Valproate (depakote) in the treatment of seizure disorders and bipolar disorders. See, for example, Mattson, et al., Department of Veterans Affairs Epilepsy Cooperative Study No. 264: A Comparison of Valproate with Carbazapine for the Treatment of Complex Partial Seizures and Secondarily Generalized Tonic-Chronic Seizures In Adults. N. Eng. J. Med., 327: 765-771 (1992); Freeman, et al., Mood Stabilizer Combinations: A Review of Safety and Efficacy. Am. J. Psychiatry, 155: 12-21 (1998); and Verity, et al., A Multi-Center Comparative Trial Of Sodium Valproate And Carbamazepine In Pediatric Epilepsy. Developmental Medicine And Child Neurology, 37: 97-108 (1993). Use of Valproate, however, is also associated with side effects in as many as 50% of the patients taking it; these side effects include marked weight gain. Isojarvi et al., Polycystic Ovaries And Hyperandrogenism In Women Taking Valproate For Epilepsy, N. Eng. J. Med., 329: 1383-1388 (1993). Although not all patients experience this weight gain side effect, in those that do, the weight gain can be considerable, as much as 40-50 pounds. This side effect presents a number of patient issues, both medical and psychological, for the treating physician to consider. Such a marked weight gain can place a significant burden on the heart and circulatory system of the patient. In addition, particularly in-patients suffering from depression, such weight gain can hurt self-image and adversely impact the depressed state. Finally, and perhaps most importantly, such side effects can reduce patient compliance with the therapy regimen, thereby resulting in ineffective treatment for the primary disorder. Identification of a means to counteract these side effects partially or completely is, therefore, important. There is at present no way to prevent or treat obesity associated with the use of Valproate, except through behavioral changes such as increased physical activity or decreased caloric intake.
Metformin is a biguanide drug which is known to improve insulin action at the cellular level, but not affect insulin secretion. Metformin is used to treat patients with non-insulin dependent diabetes and has recently been used to treat women with polycystic ovary syndrome, a syndrome characterized by hirsutism, hyperandrogenism, and polycystic ovaries. It has not, however, been suggested for use in controlling the weight gain caused by Valproate or other psychotropic actives. See, for example, Valazquez, et al, Metformin Therapy Is Associated With A Decrease In Plasma Plasminogen Activator Inhibitor-1, Lipoprotein (a) and Immunoreactive Insulin Levels In-Patients With Polycystic Ovary Syndrome. Metabolism, 46: 454-457 (1997); Valazquez, et al, Metformin Therapy In Polycystic Ovary Syndrome Reduces Hyperinsulinemia, Insulin Resistance, Hyperandrogenism, And Systolic Blood Pressure, While Facilitating Normal Menses And Pregnancy. Metabolism, 43: 647-654 (1994); Jackson, et al., Mechanism of Metformin Action In Non-Insulin Dependent Diabetes. Diabetes; 36: 632-640 (1987); Landin, et al., Treating Insulin Resistance in Hypertension With Metformin Reduces Both Blood Pressure And Metabolic Risk Factors. J. Intern. Med.; 229: 181-187 (1991); and Nestler, et al., Effects of Metformin on Spontaneous and Clomiphene-Induced Ovulation in the Polycystic Ovary Syndrome. N. Engl. J. Med. 338: 1876-1880 (1998).